Note that the industry is shifting from using the term "USB 2.0" to "Hi-Speed USB."Īn IRQ is an Interrupt ReQuest, the act of a device interrupting the CPU in order to gain its attention in an effort to send data. USB packaging and device markings frequently use the official logos shown in Figure 3-3 to distinguish the different versions of USB in common use. USB 3.0 ports run at a top speed of 4,800Mbps. USB 2.0 ports are backward-compatible with USB 1.1 devices and speeds, and manage multiple USB 1.1 devices better than a USB 1.1 port does. USB 1.1 ports run at a top speed (full-speed USB) of 12 megabits per second (Mbps), low-speed USB devices such as a mouse or a keyboard run at 1.5Mbps, and USB 2.0 (Hi-Speed USB) ports run at a top speed of 480Mbps.
Adapters are available to convert Series B cables into Mini-B cables, which support the Mini-B port design used on many recent USB devices. Cables that are Series A–to–Series A or Series B–to–Series B are used to extend standard cables, and can cause problems if the combined length of the cables exceeds recommended distances. Generally, you need a Series A–to–Series B cable to attach most devices to a USB root or external hub. Series B connectors are used for devices that employ a removable USB cable, such as a USB printer or a generic (external) hub.
Series A connectors are used on USB root hubs (the USB ports in the computer) and USB external hubs to support USB devices. USB cables use two types of connectors: Series A (also called Type A) and Series B (also called Type B). Figure 3-1 shows the rear panel of a typical ATX system, including USB and other port types discussed in this chapter. Most recent desktop systems have at least four USB ports, and many systems support as many as eight or more front- and rear-mounted USB ports.
Universal Serial Bus (USB) ports have largely replaced PS/2 (mini-DIN) mouse and keyboard, serial (COM), and parallel (LPT) ports on recent systems. Although the most important I/O port on recent systems is the USB port, you might also encounter other ports, including legacy ports such as serial and parallel, which we speak to in this section as well. In this section, we also discuss SCSI, audio connections, MIDI, and RG-6 coaxial ports. Common I/O ports include USB and FireWire. The ports are associated with copper circuits and memory ranges that allow the communication of data between the CPU, RAM, and the ports themselves. This hardware could be internal or external. I/O ports allow for connections to hardware. In this section, we detail input/output (I/O) ports. The word "port" is used often in the computer industry, and has many different meanings depending on what technology is being referred to. In this chapter you learn about serial, parallel, SCSI, USB, sound, and FireWire ports and their corresponding devices the goal is to make you proficient with the various interfaces you see in the IT field.
To fully understand how to install, configure, and troubleshoot input, output, and multimedia devices, you need to know the ports like the back of your hand. There are a plethora of ports that connect these devices to the computer, for example, the well-known USB port. Input/output (I/O) devices enable us to control the computer and display information in a variety of ways. Understanding Multimedia Devices-This section covers the basics of multimedia devices such as webcams, digital cameras, MIDI ports, microphones, sound cards, and video capture cards.Printing Fundamentals-This section describes the basics of laser, inkjet, impact, and thermal printers.Understanding Video Connector Types-This section talks about common video connectors such as VGA, DVI, and HDMI.Understanding Display Types-This section describes output devices such as CRTs, LCDs, and data projectors.Understanding Input Devices-This section describes the important characteristics of keyboards, mice, biometric readers, and other input devices.Understanding I/O Ports-This section describes the types of I/O ports used to send information to and from the processor and memory.This chapter covers the following subjects: